The present invention is directed to the field of optical fibers and, more particularly, to a method of bonding adjoining optical fibers and the resulting optical fiber assembly.
For optical communications, it is usually necessary to align and join the ends of single, one dimensional array or two dimensional array of optical fibers with other optical fibers or other optical components such as detectors, light sources, and the like, one example being a planar lightwave circuit (PLC). A connector of some sort is necessary to hold the optical fiber(s) while being joined to the other optical fibers or other optical component. Frequently, such connectors use silicon xe2x80x9cvxe2x80x9d grooves, as such structures are readily fabricated by anisotropic etching of single crystalline silicon with high precision and silicon is a very rigid material with a low thermal coefficient of expansion. See, for example, C. M. Miller, xe2x80x9cFiber-Optic Array Splicing with Etched Silicon Chips, The Bell System Technical Journal, Vol. 57 No. 1, pp. 75-90 (January 1978); C. M. Schroeder xe2x80x9cAccurate Silicon Spacer Chips for an Optical Fiber Cable Connectorxe2x80x9d, The Bell System Technical Journal, Vol. 57, No. 1, pp. 91-97 (January 1978); Blonder U.S. Pat. No. 4,810,557; Hsu et al. U.S. Pat. No. 4,911,526; Kaukeinen U.S. Pat. No. 4,923,275; and Shahid U.S. Pat. No. 5,689,599, the disclosures of which are incorporated by reference herein, which generally disclose v-groove connectors.
A connector based on a silicon v-groove array is prepared by (1) etching the v-grooves into a silicon wafer and dicing it out from the wafer, (2) bonding the optical fiber(s) between a top and bottom v-groove array, and (3) grinding and polishing the mating end of the array so that the ends of the fiber(s) are coplanar with the edges of the v-grooves. For connectors which can be attached and detached, alignment pins or other structures are added to insure alignment. For permanent connections, an optically transparent adhesive, such as an ultraviolet (UV) light curable adhesive such as that disclosed in Hinterlong et al. U.S. Pat. No. 5,394,498, the disclosure of which is incorporated by reference herein, is applied to the end of the optical fiber(s) and the edge of the v-groove connector or other optical component (which may also be a second v-groove connector). The assembly of the v-groove substrate and other optical component then are xe2x80x9cactively alignedxe2x80x9d (i.e. the light transmission is monitored while adjusting the relative positions of one v-groove substrate to the other optical component to maximize the transmitted intensity) until the alignment is satisfactory, at which point, if a UV adhesive is used, the join is exposed to UV light to cure the join.
The use of UV adhesive has the significant advantage that the join can be made rapidly in the alignment jig with no temperature excursion. However, it is necessary to make the UV adhesive layer as thin as possible as the light transmission through the join decreases as the adhesive thickness is increased due to absorption by the adhesive and loss of light which is dispersed and hence no longer confined to the optical fiber. This leads to a significant problem because if an array of optical fibers held by a silicon v-groove substrate is being joined to another optical component which does not transmit UV light, it is difficult or impossible to properly expose and cure the UV adhesive forming the join if the layer is thin. This joining problem may be further complicated by the fact that the two mating surfaces (e.g. two v-groove arrays, or a v-groove array and another component) can not sometimes be brought into very close proximity (less than 10 microns) because they may not be at exactly a 90 degree angle to the fibers and or the optical circuitry.
It is generally known that silicon is preferentially attacked by various wet etchants (e.g., KOH) and dry etching processes (including but not limited to vapor phase etching (e.g., XeF2), plasma etching and reactive ion etching (RIE)). xe2x80x9cDry etching processesxe2x80x9d will be referred to hereafter as xe2x80x9cdry etchantsxe2x80x9d. XeF2 is particularly preferred as a vapor phase etchant for silicon because of its very high selectivity for silicon (i.e., it etches silicon but little or no etching of SiO2 or polymers). Further, dry etchants are preferred over wet etchants for photonics application. Such dry etchants are usually used for pattern definition and release of so-called microelectromechanical structures (MEMS) as disclosed in, for example, P. Chu et al. xe2x80x9cControlled Pulse-Etching with Xenon Difluoridexe2x80x9d, 1997 International Conference on Solid-State Sensors and Actuatorsxe2x80x9d, Chicago, Jun. 16-19, 1997, IEEE 1997, pp. 665-668; I. Chen et al. xe2x80x9cGas Phase Pulse Etching of Silicon for MEMS with Xenon Difluoridexe2x80x9d, Proc. of the 1999 IEEE Canadian Conference on Electrical and Computer Engineering, Edmonton, Alberta, Canada, May 9-12, 1999 pp. 1637-1642; Patel et al. U.S. Pat. No. 6,290,864; Hanmin et al. Japanese Patent Application JP10313128A; and Shinji et al. Japanese Patent Application JP611811311A, the disclosures of which are incorporated by reference herein.
It would be desirable to have an improved method for joining optical fibers to a second optical component.
Accordingly, it is a purpose of the present invention to have an improved method for joining optical fibers to a second optical component.
It is another purpose of the present invention to have an improved method for joining optical fibers to a second optical component in which the optical fibers are exposed for joining.
These and other purposes of the present invention will become more apparent after referring to the following description of the invention considered in conjunction with the accompanying drawings.
The purposes of the invention have been achieved by providing, according to a first aspect of the present invention, a method of bonding optical fibers comprising the steps of:
obtaining a first optical component comprising a silicon connector;
placing at least one optical fiber in the connector;
obtaining a second optical component;
contacting the connector with a dry etchant which preferentially etches the silicon connector so as to cause the at least one optical fiber to protrude beyond the connector;
abutting the at least one optical fiber with the second optical component; and
applying an adhesive to the abutting at least one optical fiber and second optical component.
According to a second aspect of the present invention, there is provided an optical fiber assembly comprising:
a first optical component comprising a connector having a first plurality of optical fibers wherein the first plurality of optical fibers protrudes beyond the connector;
a second optical component adjacent to the connector such that the protruding first plurality of optical fibers abut the second optical component; and
an adhesive joining the abutting first plurality of optical fibers and the second optical component.